The empire of Darius I was larger than any one of the preceding empires whose growth we have traced. It included all Asia Minor and Syria, that is to say, the ancient Lydian and Hittite empires, all the old Assyrian and Babylonian empires, Egypt, the Caucasus and Caspian regions, Media, Persia, and it extended, perhaps, into India to the Indus. The nomadic Arabians alone of all the peoples of what is nowadays called the Near East, did not pay tribute to the satraps (provincial governors) of Darius. The organization of this great empire seems to have been on a much higher level of efficiency than any of its precursors. Great arterial roads joined province to province, and there was a system of royal posts;[179] at stated intervals post horses stood always ready to carry the government messenger, or the traveller if he had a government permit, on to the next stage of his journey. Apart from this imperial right-of-way and the payment of tribute, the local governments possessed a very considerable amount of local freedom. They were restrained from internecine conflict, which was all to their own good. And at first the Greek cities of the mainland of Asia paid the tribute and shared in this Persian Peace.
Darius was first incited to attack the Greeks in Europe by a homesick Greek physician at his court, who wanted at any cost to be back in Greece. Darius had already made plans for an expedition into Europe, aiming not at Greece, but to the northward of Greece, across the Bosphorus and Danube. He wanted to strike at South Russia, which he believed to be the home country of the Scythian nomads who threatened him on his northern and north-eastern frontiers. But he lent an attentive ear to the tempter, and sent agents into Greece.[180]
This great expedition of Darius opens out our view in this history. It lifts a curtain upon the Balkan country behind Greece about which we have said nothing hitherto; it carries us to and over the Danube. The nucleus of his army marched from Susa, gathering up contingents as they made their way to the Bosphorus. Here Greek allies (Ionian Greeks from Asia) had made a bridge of boats, and the army crossed over while the Greek allies sailed on in their ships to the Danube, and, two days’ sail up from its mouth, landed to make another floating bridge. Meanwhile, Darius and his host advanced along the coast of what is now Bulgaria, but which was then called Thrace. They crossed the Danube, and prepared to give battle to the Scythian army and take the cities of the Scythians.
But the Scythians had no cities, and they evaded a battle, and the war degenerated into a tedious and hopeless pursuit of more mobile enemies. Wells were stopped up and pastures destroyed by the nomads. The Scythian horsemen hung upon the skirts of the great army, which consisted mostly of foot soldiers, picking off stragglers and preventing foraging; and they did their best to persuade the Ionian Greeks, who had made and were guarding the bridge across the Danube, to break up the bridge, and so ensure the destruction of Darius. So long as Darius continued to advance, however, the loyalty of his Greek allies remained unshaken.
But privation, fatigue, and sickness hindered and crippled the Persian army; Darius lost many stragglers and consumed his supplies, and at last the melancholy conviction dawned upon him that a retreat across the Danube was necessary to save him from complete exhaustion and defeat.
In order to get a start in his retreat he sacrificed his sick and wounded. He had these men informed that he was about to attack the Scythians at nightfall, and under this pretence stole out of the camp with the pick of his troops and made off southward, leaving the camp fires burning and the usual noises and movements of the camp behind him. Next day the men left in the camp realized the trick their monarch had played upon them, and surrendered themselves to the mercy of the Scythians; but Darius had got his start, and was able to reach the bridge of boats before his pursuers came upon him. They were more mobile than his troops, but they missed their quarry in the darkness. At the river the retreating Persians “were brought to an extremity of fear,” for they found the bridge partially broken down and its northern end destroyed.
